Method for manufacturing ceramic substrate and non-fired ceramic substrate

ABSTRACT

The present invention provides a method for readily and efficiently manufacturing a ceramic substrate having an excellent dimensional accuracy and small degree of warp comprising the steps of: preparing a non-sintered multilayer ceramic body formed by laminating ceramic layers and conductor layers; forming a multilayer ceramic body-with constraint layers by adhering a first constraint layer and a second constraint layer on one major surface and the other major surface, respectively, of the multilayer ceramic body, the first and second constraint layers being prepared by dispersing a ceramic powder that is not sintered under the sintering condition of the multilayer ceramic body; firing the multilayer ceramic body with the constraint layers under the firing condition of the multilayer ceramic body; and removing the first constraint layer and the second constraint layer after sintering the multilayer ceramic body, wherein the thickness of the first constraint layer is made to be larger than the thickness of the second constraint layer, and the first constraint layer is provided on one major surface that is more largely contracted by firing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a ceramicsubstrate, particularly to a method for manufacturing a ceramicmultilayer substrate capable of surface-mounting an active member suchas a semiconductor integrated circuit member and a passive member suchas a capacitor and an inductor.

2. Description of the Related Art

Ceramic multilayer substrates for mounting chips of electronic memberssuch as semiconductor integrated circuit members (semiconductor devices)as well as chip capacitors and chip inductors are desired to have ahighly integrated wiring among high-precision integrated passive membersin order to mount the semiconductor devices and the chips of theelectronic members in high density. In addition, a low temperaturefiring type multilayer ceramic green sheet has been developed forcomplying with ever growing recent requirements of highly integratedpackaging and high operation frequencies, wherein a plurality ofinsulation ceramic green sheets having a relative dielectric constant of15 or less, on which conductor patterns comprising low resistancematerials such as Ag, Ag-Pd, Cu and Au are formed, are laminated, andthe laminated ceramic green sheets are fired all at once at atemperature as low as 1000° C. or below.

Japanese Unexamined Patent Application Publication No. 5-163072discloses a method for enabling a highly integrated wiring of theceramic multilayer substrate, wherein a multilayer ceramic body issubjected to firing while applying a relatively large pressure from theupward and downward of the non-sintered ceramic body. JapaneseUnexamined Patent Application Publication No. 4-243978 also discloses amethod comprising the steps of: laminating and press-bonding constraintceramic green sheets, which are not sintered under the firing conditionsof the non-sintered ceramic body, on both upper and lower major surfacesof the non-sintered ceramic body prepared by laminating a plurality ofceramic green sheets capable of being fired at a low temperature; firingthe ceramic green sheets under a sintering condition of the non-sinteredceramic body, and peeling and removing non-sintered layers derived fromthe constraint ceramic green sheets.

According to the methods described above, the ceramic multilayersubstrate can be formed with a quite high dimensional accuracy, becausefiring contraction along the directions on the plane of the non-sinteredceramic body, or along the directions on the X-Y plane of the substrate,may be sufficiently suppressed. In other words, the highly integratedwiring hardly causes short-circuits while allowing various kinds ofpackaging members to be mounted with high precision in the ceramicmultilayer substrate obtained.

However, a special equipment for firing under a pressure is required inthe former method described above since the multilayer ceramic body isfired while applying a relatively large pressure, leaving a problem inthe facility cost and manufacturing efficiency. Although a pressure isnot always required for firing in the latter method, it is a problemthat the multilayer ceramic body is liable to be warped due todifferences of the degree of integration of wiring and the contractionbehavior during firing between the upper layer and lower layer relativeto the center face located at an equal distance from one major surfaceand the other major surface of the non-sintered ceramic body.

The number of input-output (I/O) terminals for mounting on andconnecting to a mother board has been rapidly increased in the ceramicmultilayer substrate as the wiring pattern is highly integrated inrecent years. Also, the multilayer ceramic body is required to havehighly integrated and accurate circuit elements such as capacitors andinductors since a number of highly precise circuit elements are neededfor multi-functional and high performance ceramic multilayer substrate.Under these circumstances, a difference in the degree of contraction isliable to be caused between one major surface and the other majorsurface of the non-sintered ceramic body, generating a concave warp onthe major surface side that is able to largely contract when no pressureis applied during firing.

Japanese Unexamined Patent Application Publication Nos. 5-503498 and9-92983 disclose the methods in which constraint ceramic green sheetsare adhered onto both major surfaces of the multilayer ceramic body inorder to limit the degree of warp of the ceramic multilayer substratewithin a given range, and the multilayer ceramic green sheet is firedwhile optionally applying a uniaxial load along the vertical direction(Z-direction) of the multilayer ceramic body. The multilayer ceramicbody should be pressed with or through porous plates in the treatmentsas described above, so that volatilization of organic binders containedin the multilayer ceramic body and constraint ceramic green sheets arenot blocked.

However, a special equipment for firing under a load is also required inthe method described above as in the methods as hitherto described,leaving some problems in the facility cost and production efficiency. Inaddition, since the non-sintered ceramic body is forcibly pressed usinga porous plate, portions suffering a load and not suffering a load aredistributed on the surface of the multilayer ceramic body with finepitches corresponding to the pores on the porous plate, causing fineprojections and depressions with the foregoing pitches on the ceramicmultilayer substrate obtained.

SUMMARY OF THE INVENTION

To overcome the above described problems, preferred embodiments of thepresent invention provides a method for readily and efficientlymanufacturing a ceramic substrate having an excellent dimensionalaccuracy by suppressing deformation of the substrate such as warp of thesubstrate. One preferred embodiment of the present invention provides amethod for manufacturing a ceramic substrate having conductor patterns,comprising: adhering a first constraint layer on a first major surfaceof a non-sintered ceramic body, the first constraint layer being mainlycomposed of a first inorganic powder that is not sintered under thesintering condition of the non-sintered ceramic body; adhering a secondconstraint layer on a second major surface of the non-sintered ceramicbody, the second constraint layer being mainly composed of a secondinorganic powder that is not sintered under the sintering condition ofthe non-sintered ceramic body; and removing each of the first and secondconstraint layers after firing the non-sintered ceramic body under thesintering condition of the non-sintered ceramic body; wherein the firstconstraint, layer and the second constraint layer are made to havedifferent rigidity one another.

According to the above, since the first constraint layer and the secondconstraint layer are made to be the layers having different rigiditiesone another in the foregoing non-contraction process, the rigidities ofthe first constraint layer and the second constraint layer may beselected so as to suppress deformation of the ceramic substrate causedby firing. Accordingly, the ceramic substrate having an excellentdimensional accuracy can be easily and efficiently obtained bysuppressing deformation of the substrate such as warp of the substrate,along with suppressing firing contraction along the directions on thesubstrate plane.

Preferably, the first constraint layer is made to have a higher rigiditythan the rigidity of the second constraint layer, in order to allow thefirst constraint layer to adhere on one major surface side that is ableto be largely contracted by firing. Since the first constraint layerhaving a higher rigidity is allowed to adhere on one side of the majorsurface that may be largely contracted by firing, warp and distortion ofthe substrate ascribed to the difference of the degree of contractionbetween one major surface side and the other major surface side can besufficiently suppressed. This mean that the ceramic green sheet havingan excellent dimensional accuracy can be readily and efficientlymanufactured without using any special firing equipment by sufficientlysuppressing deformation of the substrate.

The phrase “the constraint layer having a high rigidity” as used hereinrefers to a constraint layer having a large deformation resistanceagainst the non-sintered ceramic body during firing. The phrase “onemajor surface side that is able to be largely contracted by firing”refers to a side where wiring patterns are highly integrated, a sidehaving an early onset temperature of contraction of the ceramic layer,or a side having a larger shrinkage ratio of the ceramic layer withrespect to the center face located at an equal distance from one majorsurface side and the other major surface side of the non-sinteredceramic body. The one major surface side described above alsocorresponds to the side where concave warp may be caused after firingwhen no constraint layer are formed or when rigidity of the constraintlayer is insufficient. dr

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illustrative cross section for inserting the blockmembers into the laminated body in the manufacturing process of theceramic multilayer substrate according to the first embodiment.

FIG. 2 shows an illustrative cross section for constructing themultilayer ceramic body by laminating ceramic green sheets on and underthe laminated body in the manufacturing process of the ceramicmultilayer substrate as described above.

FIG. 3 shows an illustrative cross section with the constraint layerswhen the constraint layers are adhered on the upper and lower majorsurfaces of the multilayer ceramic body in the manufacturing process ofthe ceramic multilayer substrate as described above.

FIG. 4 shows an illustrative cross section of the ceramic multilayersubstrate after peeling and removing the constraint layers in themanufacturing process of the ceramic multilayer substrate as describedabove.

FIG. 5 shows an equivalent circuit diagram of the ceramic multilayersubstrate as described above.

FIG. 6 shows an illustrative cross section of the multilayer ceramicbody with the constraint layers when the constraint layers are adheredon the upper and lower major surfaces of the multilayer ceramic body inthe manufacturing process of the ceramic multilayer substrate accordingto the second embodiment.

FIG. 7 shows an illustrative cross section of the ceramic multilayersubstrate after peeling and removing the constraint layers in themanufacturing process of the ceramic multilayer substrate as describedabove.

FIG. 8 shows an equivalent circuit diagram of the ceramic multilayersubstrate as described above.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The method for making the rigidity of the first constraint layer to behigher than the rigidity of the second constraint layer will bedescribed below. Firstly, the rigidity of the first constraint layer ismade to be higher than the rigidity of the second constraint layer byforming the first constraint layer to be thicker than the secondconstraint layer (referred as the first method hereinafter). Sincerigidity of the constraint layer is enhanced as its thickness isincreased, the rigidity of the first constraint-layer may be made to behigher than the a rigidity of the second constraint layer by allowingthe first constraint layer to be thicker than the second constraintlayer.

The thickness of each constraint layer may be appropriately adjustedduring the process for forming a constraint layer composition, preparedby dispersing an inorganic powder that is not sintered under thesintering condition of the non-sintered ceramic body into an organicbinder, into a sheet by a casting method or a doctor blade method, whenthe constraint layer comprises the ceramic green sheet. Alternatively,the thickness may be adjusted by laminating a plurality of the ceramicgreen sheets. When a paste of the constraint layer composition is coatedon both major surfaces of the non-sintered ceramic body, on the otherhand, the coating thickness or the coating times may be appropriatelyadjusted.

The first constraint layer is desirably formed to have a thickness threetimes or less as large as the thickness of the second constraint layerin the first method, because the effect of allowing the thicknesses ofrespective constraint layers to be different one another is scarcelydisplayed when the thickness of the first constraint layer exceeds threetimes or more of the thickness of the second constraint layer. Or, thebalance of the constraint force brought about by the constraint layersis destroyed to unable contraction of the non-sintered ceramic bodyalong the directions on the plane to be fully suppressed. Therefore, themore desirable thickness of the first constraint layer should beadjusted to be 1.1 to 1.6 times as large as t he thickness of thethickness of the second constraint layer, when the dimensional accuracyand the degree of warp of the substrate, and volatility of the organicbinder are taken into account.

It is made possible to depress the cost required for forming theconstraint layer besides allowing the constraint layer to be quiteeasily peeled and removed after firing, by minimizing the thickness ofthe constraint layer required for the non-contraction process, therebyenabling the manufacturing efficiency of the ceramic substrate to beimproved. In addition, a high quality ceramic substrate may bemanufactured within a short period of the firing time with less firingirregularities by suppressing generation of pores caused by residues ofthe organic binder, since the organic binder in the non-sintered ceramicbody and in the constraint layer can be smoothly volatilized.

The thicknesses of the first constraint layer and the second constraintlayer are variable depending on various factors such as the material andthe number of the ceramic layers, and the material, the degree ofintegration and the number of the layers of the wiring patterns. Inother words, the first constraint layer and the second constraint layerhaving optimum thicknesses may be appropriately selected depending onthe extent of the deformation of the substrate such as the degree ofwarp and distortion.

Secondly, the mean particle size of the inorganic power in the firstconstraint layer is made to be smaller than the mean particle size ofthe inorganic power in the second constraint layer (referred as thesecond method hereinafter). Since rigidity of the constraint layer isenhanced as the mean particle size of the inorganic powder as aprincipal component of the constraint layer is reduced, the firstconstraint layer may have a higher rigidity than the rigidity of thesecond constraint layer by selecting the mean particle size of theinorganic powder in the first constraint layer to be smaller than thatof the inorganic powder in the second constraint layer.

It is practically desirable that the mean particle size of the inorganicpowder in the first constraint layer be within a range of 0.2 to 0.8 μmwhile the mean particle size of the inorganic powder in the secondconstraint layer be within a range of 1.0 to 5.0 μm. With resect to thespecific surface area of the inorganic powder, it is desirably within arange of 4.0 to 10.0 m³/g and 1.5 to 5.0 m³/g, respectively, in thefirst constraint layer and second constraint layer. The rigidity of thefirst constraint layer may be also made to be different from therigidity of the second constraint layer, by using different kinds of theinorganic powders in respective first and second constraint layers.

Thirdly, the content of the organic binder in the first constraint layeris adjusted to be larger than the content of the organic binder in thesecond constraint layer (referred as the third method hereinafter). Whenthe first constraint layer and the second constraint layer comprise aninorganic powder dispersed in an organic binder, the rigidity of theconstraint layer may be higher as the content of the organic binder issmaller. Consequently, the rigidity of the first constraint layer turnsout to be higher than the rigidity of the second constraint layer whenthe first constraint layer contains less organic binder than the secondconstraint layer does. It is desirable that the first constraint layercontains 5 to 10 parts by weight of the organic binder and the secondconstraint layer contains 8 to 13 parts by weight of the organic binderrelative to 100 parts by weight of the inorganic powder, when the samequantity of the inorganic powder is used in the third method.

Fourth, the first constraint layer contains fibrous inorganic oxideparticles (referred as the fourth method hereinafter). Since the fibrousinorganic oxide particles contained in the constraint layer allows therigidity of the constraint layer to be higher, the rigidity of the firstconstraint layer may be adjusted to be higher than the rigidity of thesecond constraint layer by allowing the fibrous inorganic oxideparticles to be contained in the first constraint layer, or by adjustingthe content of the fibrous inorganic oxide particles in the firstconstraint layer to be higher than the content of the fibrous inorganicoxide particles in the second constraint layer. Ceramic particles suchas zirconia or alumina particles may be used for the fibrous inorganicoxide particles, wherein the ceramic particles have a favorable lengthof the longitudinal axis of about 3 to 500 μm.

Fifth, the first constraint layer contains a glass powder that does notexhibit viscous fluidity at the sintering temperature of thenon-sintered ceramic body (referred as the fifth method hereinafter).Since the constraint layer may have a higher rigidity by allowing theglass powder to be contained in the layer, the rigidity of the firstconstraint layer may be adjusted to be higher than the rigidity of thesecond constraint layer by allowing the glass powder to be contained inthe first constraint layer, or by adjusting the content of the glasspowder in the first constraint layer to be higher than the content ofthe glass powder in the second constraint layer.

However, since the constraint layer may be largely contracted due toviscous fluidity of the glass depending on the kind and quantity of theglass powder, it is desirable that a glass material that does not showviscous fluidity at the sintering temperature of the non-sinteredceramic body is selected as the-glass powder to be incorporated into theconstraint layer, besides adjusting the content of the glass powder toan extent not causing viscous fluidity (an amount that does not allowthe constraint layer to contract). The rigidity of the constraint layercan be practically enhanced to a desirable level while suppressingcontraction of the constraint layer itself, by allowing the glass powder(for example, a silicate glass powder) having a softening temperature of800° C. or above to be contained in the constraint layer when thenon-sintered ceramic body has a sintering temperature of about 900 to1000° C.

While the methods for making the first constraint layer to have higherrigidity than that of the second constraint layer have been hithertodescribed, an appropriate combination among the first to fifth methodsmay be applied in the present invention. Various combinations of themethods are possible such as, for example, allowing the thickness of thefirst constraint layer to be larger than the thickness of the secondconstraint layer, besides making the mean particles size of theinorganic powder-in the first constraint layer to be smaller than themean particles size of the inorganic powder in the second constraintlayer.

The first and second constraint layers may desirably comprise theceramic green sheet prepared by dispersing the inorganic powder into theorganic binder. An inorganic oxide powder such as alumina, zirconia,magnesia, mulllite and quartz, and a non-oxide inorganic powder such asboronitride may be practically used for the first and second constraintlayers. For example, a ceramic green sheet, in which the inorganic oxidepowder is dispersed in an organic powder volatile during firing of thenon-sintered ceramic body, is favorably used as a constraint layercomposition for forming into a sheet.

As hitherto described, the first constraint layer and the secondconstraint layer are not necessarily restricted for use as green sheets,but they may comprise the layers formed by coating a paste composition,or may be formed by a spray or immersion method. Otherwise, aplasticizer, a parting agent, a dispersing agent, or a peeling agent maybe added into the constraint layer composition.

At least one kind of the passive member selected from a group consistingof a capacitor, an inductor and a resistor may be integrated into thenon-sintered ceramic body according to the present invention. Whenvarious kinds of the passive members are integrated into thenon-sintered ceramic body, the degree of integration of the patternsconstituting the passive members may be different between one majorsurface side and the other major surface side of the non-sinteredceramic body to arise a different degree of contraction by firingbetween the two major surfaces, thereby making the substrate to bereadily deformed. Deformation of the substrate such as warp anddistortion may be well suppressed, on the contrary, by allowing thefirst constraint layer having a higher rigidity than the rigidity of thesecond constraint layer to adhere on one major surface side that may belargely contracted by firing.

Capacitors and inductors may be incorporated into the non-sinteredceramic body as block members. However, warp and distortion may becaused by the difference of the degree of contraction between one majorsurface side and the other major surface side ascribed to the differencebetween the contraction behavior of dielectric materials or magneticmaterials constituting respective block members, and the contractionbehavior of the non-sintered ceramic body (particularly the differenceof the contraction onset temperature and shrinkage ratio), when thecapacitor and inductor are formed into non-sintered blocks to integratethem into the prescribed locations in the non-sintered ceramic body.Warp and distortion of the substrate can be well suppressed, on thecontrary, when the first constraint layer having a higher rigidity thanthe rigidity of the second constraint layer is adhered on one majorsurface side that may be largely contracted by firing the non-sinteredceramic body. The passive members to be integrated in the presentinvention are not necessarily restricted to elementary members such asthe capacitors and inductors, but a composite of them, for example a LCcomposite member in which the capacitors and inductors are combined, maybe available. Although the block member is desirably a non-sinteredblock, a block member (a chip member) after firing may be used.

The non-sintered ceramic body is desirably fired at a temperature of1000° C. or below. It is also desirable to constitute the non-sinteredceramic body with a ceramic material known in the art such as acrystalline glass based, a composite glass based or a non-glass basedmaterial that is sintered at a low temperature. When the non-sinteredceramic body is constructed with the material as described above, a lowmelting point metallic material such as Ag, Ag-Pd, Ag-Pt, Cu and Au maybe used for the conductor pattern to serve as electrodes and wiring,thereby enabling to comply with the requirements of making the signalshigh speed and high frequency. However, the materials for the conductorpattern are not limited to those as described above, but other metallicmaterials such as Ni, Pt, Pd, W and Mo may be used.

The non-sintered ceramic body may be provided with such characteristicsas insulation property, dielectric property and magnetic property. Thematerial may desirably contain a glass component with a softeningtemperature of 800° C. or below, and it is advantageous for allowing theconstraint force of the constraint layer to be fully exhibited that thecontent of the glass component (a filler component) is selected to bewithin a range of 5 to 100 parts by weight.

The non-sintered ceramic body desirably contains a liquid phase formingmaterial such as, for example, lead oxide and bismuth oxide that forms aliquid phase at a temperature of 900° C. or below. The content of theliquid phase forming material is advantageously selected to be within arange of 5 to 100 parts by weight relative to the ceramic component.

The non-sintered ceramic body according to the present invention may befired without applying any load. A ceramic multilayer substrate havingan excellent dimensional accuracy and few distortion of the substratecan be readily and efficiently manufactured without providing a specialequipment for firing under a load. A ceramic multilayer substrate havinggood surface smoothness may be also obtained without forming any fineroughness caused by the porous plate on the surface of the ceramicsubstrate obtained.

However, the present invention is not necessarily restricted to themethod without applying any load during firing, but the non-sinteredceramic body may be fired under a given load. For example, thenon-sintered ceramic body is subjected to a firing treatment whileapplying a uniaxial load of 10 kg/cm² or less against the non-sinteredceramic body provided with the constraint layers.

The method for manufacturing the ceramic substrate according to thepresent invention will be described hereinafter with reference to theembodiments.

First Embodiment

The method for manufacturing the ceramic multilayer substrate accordingto the first embodiment will be described with reference to FIGS. 1 to5.

A non-sintered molded block to serve as a capacitor C and a non-sinteredmolded block to serve as an inductor L are prepared as shown in FIG. 1.The molded block for the capacitor C comprises a multilayer structure inwhich inner electrodes are laminated via a dielectric ceramic-greensheet mainly composed of a dielectric ceramic powder. Terminalelectrodes are formed on both opposite sides faces of the molded block,respectively, and the inner electrodes to be connected to one terminalelectrode and the inner electrodes to be connected to the other terminalelectrode are alternately laminated as seen in conventional multilayerceramic capacitors.

The molded block for the inductor L comprises, on the other hand, amultilayer structure in which the inner electrodes are laminated via amagnetic ceramic green sheet mainly composed of a magnetic ceramicpowder. Terminal electrodes are formed on both opposite end faces of themolded block, and respective inner electrodes are connected withvia-holes perforating through the magnetic ceramic green sheet tototally form a conductor pattern elongating as a coil.

The molded block for the capacitor C and the molded block for theinductor L are constructed so as to be able to be fired at a temperatureof 1000° C. or below. Ceramic functional materials as principalcomponents of the dielectric ceramic green sheet and the magneticceramic green sheet, or materials prepared by adding a glass into thedielectric ceramic material and the magnetic ceramic material, or acrystalline glass itself, is used for the purpose as described above.

A ceramic slurry prepared by dispersing a mixed powder, in which a smallamount of a borosilicate glass is mixed into barium titanate, into anorganic vehicle is formed into a sheet by a doctor blade method for usein the dielectric ceramic green sheet that is practically used.Similarly, a ceramic slurry prepared by dispersing a mixed powder, inwhich a small amount of a borosilicate glass is mixed into nickel zincferrite, into an organic vehicle is formed into a sheet by a doctorblade method for use in the magnetic ceramic green sheet that ispractically used. In addition, the inner electrodes and terminalelectrodes and constituting the capacitor C, and the inner electrodes,terminal electrodes and via-holes constituting the inductor L may beformed, for example, using a conductor paste containing a metal or analloy such as Ag, Ag-Pt, Ag-Pd, Cu or Au.

The molded block for the capacitor C, and the molded block for theinductor L are desirably formed by a press-bonding process afterlaminating a given number of the dielectric ceramic green sheets inwhich the inner electrodes are formed, and a give number of ceramicgreen sheets in which the inner electrodes and via-holes are formed,respectively. A pressure of about 200 kg/cm² is suitable forpress-bonding.

For forming the laminated body 4 shown in FIG. 1, on the other hand,insulation ceramic green sheets 1 c, 1 d, 1 e and 1 f are prepared. Aceramic slurry prepared by dispersing a mixed powder, in which a glasspowder is mixed with an insulation ceramic powder, is formed into asheet by a doctor blade method for preparing each of the insulationceramic green sheet 1 c, 1 d, 1 e and 1 f. The laminated body 4 alsocomprises a laminated body in which the ceramic green sheets 1 c, 1 d, 1e and 1 f formed to provide a via-hole 2 f and spaces 3 a and 3 b aresequentially laminated.

The bolded block for the capacitor C and the molded block for theinductor L are inserted into the spaces 3 a and 3 b of the laminatedbody 4 as shown in FIG. 1. Each terminal electrode of the individualmolded block is accordingly exposed from the open face of the spaces 3 aand 3 b. The blocks are then press-bonded with a hydraulic press at apressure of about 500 kg/cm² to form the laminated body 4 in which themolded block for the capacitor c and the molded block for the inductor Lare integrated. Adhesion among the ceramic green sheets 1 c, 1 d, 1 eand 1 f containing the molded block for the capacitor C and the moldedblock for the inductor L can be enhanced by subjecting the laminatedbody 4 to the press-bonding process, while each molded block is tightlyadhered to the inner circumference wall of the space.

Then, insulation ceramic green sheets 1 a and 1 b are laminated on theupper face of the laminated body 4 in which the molded block for thecapacitor C and the molded block for the inductor L are integrated asshown in FIG. 2, followed by laminating and press-bonding an insulationceramic green sheet 1 g on the lower face side of the laminated body. Anon-sintered multilayer ceramic body 1 is formed by the processdescribed above.

The via-holes 2 a and 2 b are formed on the insulation ceramic greensheet 1 a, while the via-hole 2 c, inner conductor patterns 5 a and 5 b,and a thick-film resistor R are formed on the insulation ceramic greensheet 1 b. The via-holes 2 a is formed so as to be in electricalcontinuity with the via-holes 2 c and 2 f, while the via-hole 2 b isformed so as to be in electrical continuity with the inner conductorpattern 5 b. One end of the thick-film resistor R is put into electricalcontinuity with one of the terminal electrode of the capacitor C via theinner conductor pattern 5 a and the via-hole 2 d, while the other end ofthe thick-film resistor R is put into electrical continuity with oneterminal electrode of the inductor L via the inner conductor pattern 5 band the via-hole 2 e. An inner conductor pattern 5 c is formed on theinsulation ceramic green sheet 1 g, and the inner conductor pattern 5 cis put into electrical continuity with the via-hole 2 f, the otherterminal electrode of the capacitor C and the other terminal electrodeof the inductor L.

The ceramic green sheet 1 a, 1 b and 1 g are prepared by forming aceramic slurry, in which a mixed powder of an insulation ceramic and aglass is dispersed into an organic vehicle, into a sheet by a doctorblade method as described above. The inner conductor patterns 5 a, 5 band 5 c, and the via-holes 2 a, 2 b, 2 c, 2 d and 2 e may be formedusing a conductor paste containing, for example, Ag, Ag-Pt, Ag-Pd, Cu,Ni, Pt, Pd, W, Mo and Au, and can be printed to be desired patterns by ascreen printing. The thick film resistor R is also formed by a screenprinting of the conductor paste, wherein a paste prepared by dispersinga mixed powder of ruthenium oxide and a small amount of borosilicateglass into an organic vehicle may be used.

The insulation ceramic powder used as a principal component of theinsulation ceramic green sheets 1 a, 1 b, 1 c, 1 d, 1 e, 1 f and 1 g isable to fire at a temperature of 1000° C. or below. For example, theinsulation ceramic powder capable of firing at a relatively lowtemperature of 1000° C. or below may be obtained when the insulationceramic powder contains a glass powder with a softening point of 800° C.or below, or a liquid phase forming material that forms a liquid phaseat 900° C. or below, and when the content of the glass powder or theliquid phase forming material is selected to be within a range of 5 to100 parts by weight relative to 100 parts by weight of the ceramicpowder. When the content of the glass powder or the liquid phase formingmaterial is less than 5 parts by weight, the firing temperature tends tobe higher than 1000° C. It is not preferable that the firing temperatureis high because the selection range of the foregoing materials turns outto be narrow. Practically available ceramic green sheet is obtained bymolding a ceramic slurry, prepared by dispersing a mixed powder ofborosilicate glass and alumina into an organic vehicle, into a sheet bya doctor blade method. Such insulation ceramic green sheet can be firedat a relatively low temperature of 800 to 1000° C.

A multilayer ceramic body with constraint layers is formed by adhering afirst constraint layer 7 a and a second constraint layer 7 b on onemajor surface 6 a and the other major surface 6 b, respectively, of themultilayer ceramic body 1 formed by sequentially laminating andpress-bonding the insulation ceramic green sheet 1 a, the insulationceramic green sheet 1 b, the laminated body 4 and the ceramic greensheet 1 g as shown in FIG. 3. The multilayer ceramic body withconstraint layers is mounted on a setter 9 and placed in a firingequipment.

The first constraint layer 7 a and the second constraint layer 7 bcomprise the'sheets of constraint layers prepared by dispersing anon-sintered ceramic powder, which is not sintered under the firingcondition of the multilayer ceramic body 1, into an organic binder.Since all of the molded block for the capacitor C and the molded blockfor the inductor L, and the insulation ceramic green sheets 1 a, 1 b, 1c, 1 d, 1 e, 1 f and 1 g are able to be fired at a temperature of 1000°C. or below, the multilayer ceramic body 1 as a composite of thesemembers is also possible to be fired at a temperature of 1000° C. orbelow. In other words, the constraint layers 7 a and 7 b may beconstituted with the ceramic powder that is not sintered at atemperature of 1000° C. or below.

The constraint layers 7 a and the constraint layer 7 b are provided tobe adhered on respective major surfaces located at both ends along thedirection of lamination of the multilayer ceramic body 1, or on onemajor surface 6 a and the other major surface 6 b, respectively. Theconstraint layers are press-bonded thereafter together with themultilayer ceramic body 1. A hydraulic press at a pressure of about 1000kg/cm² is favorably used for press-bonding.

The first constraint layer 7 a has a thickness of T1 and the secondconstraint layer 7 b has a thickness of T2. The multilayer ceramic body1 shows concave warp toward one major surface 6 a side when one majorsurface 6 a of the multilayer ceramic body 1 is more largely contractedthan the other constraint layer 6 b is, or when the first constraintlayer and the second constraint layer have the same thickness oneanother and their rigidity is insufficient. Adcordingly, the firstconstraint layer 7 a is formed to have a larger thickness T1 than thethickness T2 of the second constraint layer 7 b. In other words, therigidity of the first constraint layer 7 a becomes higher than therigidity of the second constraint layer 7 b when the relation of T1>T2is valid.

It is desirable that the thickness T1 of the first constraint layer 7 ais three times or less as large as the thickness T2 of the secondconstraint layer 7 b as hitherto described. However, since thethicknesses T1 and T2 are variable depend on the material and number ofsheets of the ceramic layer, and the material of the conductor pattern,the degree of integration and the number of the layers of the conductorpattern, in addition to the degree of integration of wiring pattern andconstituting members of the multilayer ceramic body, the thickness maybe appropriately selected.

Subsequently, the molded block for the capacitor C and the molded blockof the inductor L are fired at a temperature of about 900° C. in the airwithout applying any load to sinter the molded block for the capacitor Cand the molded block for the inductor L into the sintered capacitor Cand sintered inductor L, respectively, besides sintering the insulationceramic green sheets 1 a, 1 b, 1 c, 1 d, 1 e, 1 f and 1 g, therebyobtaining the ceramic multilayer substrate 10 as a sintered body of themultilayer ceramic body 1.

After cooling these members, the first constraint layer 7 a and thesecond constraint layer 7 b are removed. Since each constraint layerremains to be a porous layer comprising the non-sintered ceramic powder,it can be peeled and removed by various methods such as wet horningmethod and sand blast method. While a reaction phase may be formed atthe interface between each constraint layer and the ceramic multilayersubstrate (or the interface between the constraint layer and the surfaceconductor layer), the reaction layer may be removed by the foregoing wethorning method and sand blast method, or may be left behind providedthat it does not affect the characteristics of the ceramic multilayersubstrate 10.

The capacitor C, the inductor L and the thick-film resistor R as passivemembers are integrated into the ceramic multilayer substrate 10 obtainedby the method as described above as shown in FIG. 4. An inner conductorpattern using the capacitor C, the inductor L and the thick filmresistor R as circuit elements, and via-holes are also formed in theceramic multilayer substrate 10. The ceramic multilayer substrate 10comprising the circuit construction as shown in FIG. 5 is formed byproviding external terminals 12 a and 12 b on one major surface of theceramic multilayer substrate.

According to the method for manufacturing the ceramic multilayersubstrate in this embodiment, the first constraint layer 7 a and thesecond constraint layer 7 b that are not sintered under the sinteringcondition of the multilayer ceramic body 1 are adhered on the one majorsurface 6 a and the other major surface 6 b, respectively, of themultilayer ceramic body 1, wherein the first constraint layer 7 a ismade to be a constraint layer having a higher rigidity than the rigidityof the second constraint layer 7 b, and the first constraint layer 7 ais adhered on the one major surface 6 a side that is largely contractedby firing. As a result, warp of the substrate that may caused by thedifference of the degree of contraction between the one major surface 6a side and the other major surface 6 b side can be minimized. Sincecontraction by firing along the directions on the substrate plane may bealso suppressed, the ceramic multilayer substrate 10 having an excellentdimensional accuracy is obtainable. In addition, since the firingtreatment is carried out without applying any load, no specialequipments are used thereby to readily and efficiently manufacture theceramic multilayer substrate 10.

The optimum thickness of the first constraint layer 7 a and the secondconstraint layer 7 b in the embodiment shown in FIGS. 1 to 5 will bedescribed below.

The case when the first constraint layer 7 a has the same thickness asthe thickness of the second constraint layer 7 b, or when the ratiobetween the thickness T1 of the first constraint layer 7 a and thethickness T2 of the second constraint layer 7 b is 1.0 while maintainingthe rigidity of both layers to be equal, will be described first. Thethickness of each constraint layer was changed within a range of 0.05 mmto 2.0 mm, and the shrinkage ratio, dimensional irregularity, and thedegree of warp of the ceramic multilayer substrate 10 were measured. Theresults of measurements are shown in TABLE 1 below, in which thethickness of the multilayer ceramic body is fixed to 1 mm. The cells inthe table where no measured data are filled means that the measurementwas impossible due to large degree of warp (the same hereinafter).

TABLE 1 THICKNESS THICKNESS OF FIRST OF SECOND CONSTRAINT CONSTRAINTSHRINKAGE DIMENSIONAL DEGREE OF LAYER LAYER RATIO OF RATIO DISTRIBUTIONWARP EXAMPLE (mm) (mm) THICKNESS (%) (%) (μm/INCH²)  1 2.0 2.0 1.0 0.100.10  20  2 1.6 1.6 1.0 0.10 0.10  20  3 1.4 1.4 1.0 0.10 0.10  30  41.2 1.2 1.0 0.10 0.10  35  5 1.0 1.0 1.0 0.10 0.10  40  6 0.8 0.8 1.00.10 0.10  45  7 0.6 0.6 1.0 0.10 0.10  50  8 0.5 0.5 1.0 0.10 0.10  60 9 0.4 0.4 1.0 0.12 0.12 120 10 0.3 0.3 1.0 0.15 0.18 150 11 0.2 0.2 1.00.56 0.23 180 12 0.1 0.1 1.0 3.55 0.25 300 13  0.05  0.05 1.0 — — 2000 

TABLE 1 shows that a ceramic multilayer substrate in which irregularityin the shrinkage ratio and dimensional accuracy is suppressed and havingsmall degree of warp besides being excellent in dimensional accuracy canbe obtained at a thickness of each constraint layer of 1.4 mm or more,when the thickness T1 of the first constraint layer 7 a is equal to thethickness T2 of the second constraint layer 7 b. However, the degree ofwarp as well as irregularity of the shrinkage ratio and dimensionalaccuracy tend to increase as the thickness of each constraint layer isreduced. Accordingly, although a thickness of each constraint layer of0.5 mm or more is sufficient for sufficiently reducing the dimensionalirregularity of the ceramic multilayer substrate, a thickness of eachconstraint layer of 1.6 mm or more is additionally needed in order tosufficiently suppress the degree of warp of the substrate.

The case when the thickness T1 of the first constraint layer 7 a isdifferent from the thickness T2 of the second constraint layer 7 b, orwhen the thickness T1 of the first constraint layer 7 a is larger thanthe thickness T2 of the second constraint layer 7 b to allow the firstconstraint layer 7 a to serve as a constraint layer having a higherrigidity, and the first constraint layer 7 a is adhered on one majorsurface 6 a side that is more largely contracted by firing, will be thendescribed. The shrinkage ratio, dimensional irregularity and the degreeof warp of the ceramic multilayer substrate 10 were determined. Theresults of measurements are shown in TABLE 2 below. The thickness of themultilayer ceramic body 1 was adjusted to 1 mm as in the cases describedabove.

TABLE 2 THICKNESS THICKNESS OF FIRST OF SECOND CONSTRAINT CONSTRAINTSHRINKAGE DIMENSIONAL DEGREE OF LAYER LAYER RATIO OF RATIO DISTRIBUTIONWARP EXAMPLE (mm) (mm) THICKNESS (%) (%) (μm/INCH²) 14 0.80 0.80 1.00.10 0.10 45 15 0.80 0.72 1.1 0.10 0.10 35 16 0.80 0.67 1.2 0.10 0.10 2617 0.80 0.62 1.3 0.10 0.10 22 18 0.80 0.57 1.4 0.10 0.10 20 19 0.80 0.531.5 0.10 0.10 20 20 0.80 0.50 1.6 0.10 0.10 25 21 0.80 0.47 1.7 0.100.10 55 22 0.80 0.44 1.8 0.10 0.10 70 23 0.80 0.42 1.9 0.10 0.10 120  240.80 0.40 2.0 0.11 0.10 150  25 0.70 0.50 1.4 0.10 0.10 20 26 0.60 0.431.4 0.10 0.10 20 27 0.50 0.36 1.4 0.12 0.10 22

TABLE 2 shows that the shrinkage ratio and dimensional irregularity aswell as the-degree of warp of the substrate can be suppressed byadjusting the thickness T1 of the first constraint layer 7 a and thethickness T2 of the second constraint layer 7 b to be in an optimumratio, when the thickness T1 of the first constraint layer 7 a is madeto be larger than the thickness T2 of the second constraint layer 7 b,and when the first constraint layer 7 a is adhered on one major surface6 a side that is more largely contracted by firing. The shrinkage ratioand dimensional irregularity as well as the degree of warp of thesubstrate can be minimized, particularly when the ratio of the thicknessT1 of the first constraint layer 7 a against the thickness T2 of thesecond constraint layer is adjusted to about 1.1 to 1.6 even if thethickness T1 of the first constraint layer 7 a is as thin as 0.5 to 0.8mm.

A thickness T1 of the first constraint layer 7 a and a thickness T2 ofthe second constraint layer 7 b of 0.60 mm and 0.43 mm, respectively,are sufficient for suppressing the dimensional irregularity and thedegree of warp of the substrate. In other wards, the required quantityof the constraint layer can be reduced to one third of the quantity ofeach constraint layer when the thickness is 1.6 mm or more. It was alsorevealed to be desirable that the thickness T1 of the first constraintlayer 7 a is three times or less as large as the thickness T2 of thesecond constraint layer 7 b, since the effect of reducing the thicknessof the constraint layer is seldom displayed even when the thickness T1of the first constraint layer 7 a exceeds three times or more of thethickness T2 of the second constraint layer 7 b. Provided that thedegree of warp of the substrate be minimized within an area where theratio between the first constraint layer and the second constraint layerexceeds three, but the constraint layer is peeled off from the substratedue to deformation of the constraint layer accompanied by the warp ofthe substrate.

The cost required for the constraint layer is depressed besides enablingthe constraint layer to be quite easily peeled and removed, by allowingthe thickness of the constraint layer required for applying thenon-contraction process to be minimized, thereby largely improving themanufacturing efficiency of the ceramic multilayer substrate.Restricting the thickness of each constraint layer within a minimalessential thickness allows the organic binder in the multilayer ceramicbody, and the organic binder in the constraint layer, to be smoothlyvolatilized during firing, which enables the firing time to be reducedand a high quality of ceramic multilayer substrate containing lessfiring irregularity to be obtained.

Since the ceramic green sheet does not substantially show anycontraction along the directions on the X-Y plane, it is made easy tomake respective contraction behaviors of the molded blocks and ceramicgreen sheets to be matched one another when various kinds of the moldedblocks and the ceramic green sheets are simultaneously fired.Accordingly, the selection range of the materials of the molded blocksand the ceramic green sheets can be further expanded.

Since block members such as the capacitor C and the inductor L arecompletely buried into the laminated body, environment resistance suchas moisture resistance of these passive members are improved. Theselection range of the commercial design considering the specificationand cost of the product may be expanded and cross-talk of signals may beavoided, because not only two-dimensional arrangement but alsothree-dimensional arrangement of these block members is possible.

Since the integrated non-sintered molded blocks can be fired togetherwith the non-sintered multilayer ceramic body, contraction behaviors ofthem during firing should not be so strictly controlled as compared withthe case when the multilayer ceramic body is fired together with theburied and previously fired block members, thereby enabling to expandthe selection range of the materials for the ceramic green sheets andmolded blocks.

The ceramic multilayer substrate can maintain better planarity than theceramic multilayer substrate in which passive members are constructed bya lamination method does, because spaces for inserting the molded blocksto serve as passive members have been previously provided in thenon-sintered multilayer ceramic body. Consequently, highly integratedwiring is made possible with high dimensional accuracy while eliminatingits characteristics to be irregular, since deformation, and breakage ofwiring conductors are hardly caused. The number of the ceramic layersprovided in the ceramic multilayer substrate is readily increased ordecreased to consequently make it easy for the ceramic multilayersubstrate to have high performance.

The multilayer structure of the molded block to serve as a passivemember allows a large capacitance capacitor to be obtained when thepassive member is a capacitor, or a high inductance inductor to beobtained when the passive member is an inductor.

While the multilayer ceramic body is fired without applying any load inthis embodiment, it is also effective to optionally apply a load inorder to further reduce the degree of warp of the substrate. A quite lowload of 50 g/cm² is sufficient for obtaining a sufficient effect. Thecapacitor, the inductor and the thick-film resistor according to thisembodiment have been confirmed to exhibit the characteristics asdesigned.

Second Embodiment

The method for manufacturing the ceramic multilayer substrate accordingto the second embodiment will be described hereinafter with reference toFIGS. 6 to 8.

A multilayer ceramic body 23 is prepared as shown in FIG. 6, in whichinsulation ceramic green sheets 21 a, 21 b, 21 c, 21 d and 21 e, anddielectric ceramic green sheets 22 a and 22 b are laminated. Amultilayer ceramic body with constraint layers is also prepared, inwhich a first constraint layer 25 a is adhered on one major surface 24 aof the multilayer ceramic body 23, and a second constraint layer 25 b isadhered on the other major surface 24 b of the multilayer ceramic body23. The multilayer ceramic body is mounted on a setter 9 to place it ina firing equipment.

A capacitor C1, a capacitor C2 and a thick-film resistor R are formedwithin the multilayer ceramic body 23, and a prescribed circuit isconstructed with via-holes and inner layer conductor patterns. Eachcapacitor is formed by laminating ceramic green sheets on which adesired conductor pattern has been formed, and dielectric ceramic greensheets 22 a and 22 b having a high dielectric constant are providedbetween one electrode and the other electrode constituting eachcapacitor, thereby forming the large capacitance capacitors C1 and C2.

The first constraint layer 25 a has a thickness T3 while the secondconstraint layer has a thickness T4. Since one major surface 24 a sideof the multilayer ceramic body 23 has a larger shrinkage ratio than theother major surface 24 b side in this embodiment, the first constraintlayer 25 a is formed to have a larger thickness T3 than the thickness T4of the second constraint layer 25 b. That is, rigidity of the firstconstraint layer 25 a turns out to be higher than the rigidity of thesecond constraint layer 25 b when the relation of T3>T4 is valid.

After firing the multilayer ceramic body as shown in FIG. 6 at about900° C. in the air without applying any load, the first constraint layer25 a and the second constraint layer 25 b are removed. Then, a ceramicmultilayer substrate 26 comprising external electrodes 27 a and 27 b onone major surface and integrating the capacitors C1 and C2, and thethick-film resistor R is obtained as shown in FIG. 7. The ceramicmultilayer substrate 26 comprises a circuit construction as shown inFIG. 8.

According to the method for manufacturing the ceramic multilayersubstrate of this embodiment, the first constraint layer 25 a and thesecond constraint layer 25 b, which are prepared by dispersing aninorganic oxide powder that is not sintered under the sinteringcondition of the multilayer ceramic body 23 in an organic binder, areadhered, respectively, on one major surface 24 a and the other majorsurface 24 b of the multilayer ceramic body 23, wherein the firstconstraint layer 25 a is made to be a layer having a higher rigiditythan that of the second constraint layer 25 b and wherein the firstconstraint layer 25 a is adhered on one major surface 24 a side that maybe largely contracted by firing. Consequently, the degree of warp of thesubstrate that may caused by the difference of the shrinkage ratiobetween one major surface 24 a side and the other major surface 24 bside of the multilayer ceramic body 23 can be minimized. A ceramicmultilayer substrate 26 having an excellent dimensional accuracy can bealso obtained by suppressing firing contraction along the directions onthe substrate plane. Moreover, the ceramic multilayer substrate asdescribed above can be easily and efficiently obtained without using anyspecial firing equipment, because the ceramic multilayer substrate isfired without applying any load.

An optimum thickness of the first constraint layer 25 a and the secondconstraint layer 25 b in the embodiment shown in FIGS. 6 to 8 will bedescribed below.

First, the first constraint layer 25 a has the same thickness as that ofthe second constraint layer 25 b, or the ratio between the thickness T3of the first constraint layer 25 a and the thickness T4 of the secondconstraint layer 25 b is 1.0 to make rigidity of both layers to beequal. The thickness of each constraint layer was changed in a range of0.05 mm to 2.0 mm in this example, and the shrinkage ratio, dimensionalirregularity and the degree of warp of the ceramic multilayer substrate26 obtained by the foregoing manufacturing method were determined. Theresults of measurements are shown in TABLE 3. The thickness of themultilayer ceramic body was adjusted to 1 mm in these examples.

TABLE 3 THICKNESS THICKNESS OF FIRST OF SECOND CONSTRAINT CONSTRAINTSHRINKAGE DIMENSIONAL DEGREE OF LAYER LAYER RATIO OF RATIO DISTRIBUTIONWARP EXAMPLE (mm) (mm) THICKNESS (%) (%) (μm/INCH²) 28 2.0 2.0 1.0 0.100.10  15 29 1.6 1.6 1.0 0.10 0.10  15 30 1.4 1.4 1.0 0.10 0.10  15 311.2 1.2 1.0 0.10 0.10  23 32 1.0 1.0 1.0 0.10 0.10  40 33 0.8 0.8 1.00.10 0.10  46 34 0.6 0.6 1.0 0.10 0.10  55 35 0.5 0.5 1.0 0.10 0.10  7036 0.4 0.4 1.0 0.12 0.12 120 37 0.3 0.3 1.0 0.15 0.18 150 38 0.2 0.2 1.00.56 0.23 200 39 0.1 0.1 1.0 3.55 0.25 350 40  0.05  0.05 1.0 — — 2000 

TABLE 3 shows that a ceramic multilayer substrate in which irregularityof the shrinkage ratio and dimensional irregularity are suppressed whilehaving less degree of warp and excellent dimensional accuracy can beobtained at a thickness of each constraint layer of 1.2 mm or more, whenthe thickness T3 of the first constraint layer 25 a is adjusted to bethe same as the thickness of T4 of the second constraint layer 25 b.However, the degree of warp of the substrate as well as the irregularityof the shrinkage ratio and dimensional irregularity showed tendencies toincrease as the thickness of each constraint layer is reduced. Althougha thickness of 0.5 mm or more of each constraint layer relative to thethickness of 1 mm of the non-sintered multilayer ceramic body 23 issufficient for sufficiently reducing the dimensional irregularity of theceramic multilayer substrate, a thickness of 1.4 mm or more of eachconstraint layer is additionally required for more sufficiently reducethe degree of warp of the substrate.

The case when the thickness T3 of the first constraint layer 25 a ismade to be different from the thickness T4 of the second constraintlayer 25 b, or when the thickness T3 of the first constraint layer 25 ais made to be larger than the thickness T4 of the second constraintlayer 25 b to allow the first constraint layer 25 a to serve as aconstraint layer having a higher rigidity, and the first constraintlayer 25 a is adhered on one major surface 24 a side that may be largelycontracted by firing, will be then described. The shrinkage ratio,dimensional irregularity and the degree of warp of the ceramicmultilayer substrate 26 obtained were determined the results ofmeasurements are shown in TABLE 4.

TABLE 4 THICKNESS THICKNESS OF FIRST OF SECOND CONSTRAINT CONSTRAINTSHRINKAGE DIMENSIONAL DEGREE OF LAYER LAYER RATIO OF RATIO DISTRIBUTIONWARP EXAMPLE (mm) (mm) THICKNESS (%) (%) (μm/INCH²) 41 0.80 0.80 1.00.10 0.10 46 42 0.80 0.72 1.1 0.10 0.10 23 43 0.80 0.67 1.2 0.10 0.10 2044 0.80 0.62 1.3 0.10 0.10 16 45 0.80 0.57 1.4 0.10 0.10 15 46 0.80 0.531.5 0.10 0.10 15 47 0.80 0.50 1.6 0.10 0.10 28 48 0.80 0.47 1.7 0.100.10 60 49 0.80 0.44 1.8 0.10 0.10 70 50 0.80 0.42 1.9 0.10 0.10 120  510.80 0.40 2.0 0.11 0.10 160  52 0.70 0.50 1.4 0.10 0.10 15 53 0.60 0.431.4 0.10 0.10 15 54 0.50 0.36 1.4 0.12 0.10 18

TABLE 4 shows that irregularities of the shrinkage ratio and dimensionas well as the degree of warp may be suppressed by appropriatelyadjusting the ratio between the thickness T3 of the first constraintlayer 25 a and the thickness T4 of the second constraint layer 25 b,when the thickness T3 of the first constraint layer 25 a is adjusted tobe larger than the thickness of T4 of the second constraint layer 25 b,and the first constraint layer 25 a is adhered on one major surface 24 aside having a larger shrinkage ratio by firing. It can be alsounderstood that irregularities of the contraction ratio and dimension aswell as the degree of warp may be minimized by adjusting the ratiobetween the thickness T3 of the first constraint layer 25 a and thethickness of T4 of the second constraint layer 25 b to about 1.1 to 1.6,even when the thickness T3 of the first constraint layer 25 a is as thinas about 0.5 mm to 0.8 mm.

When the thickness T3 of the first constraint layer 25 a and thethickness of T4 of the second constraint layer 25 b is 0.60 mm and 0.43mm, respectively, the dimensional irregularity as well as the degree ofwarp of the substrate can be sufficiently reduced, thereby enabling therequired quantity of the constraint layer to be one third as small asthat of each constraint layer having a thickness of 1.4 mm or more.

The cost required for the constraint layer is depressed besides enablingthe constraint layer to be quite easily peeled and removed by minimizingthe thickness of the constraint layer, thereby largely improving themanufacturing efficiency of the ceramic multilayer substrate. When thethickness of each constraint layer is restricted within a minimumessential range, the organic binder in the multilayer ceramic body andin the constraint layer is smoothly volatilized during firing to enablethe firing time to be shortened, thereby enabling a high quality ceramicmultilayer substrate to be obtained with little firing irregularity.

Third Embodiment

The optimum mean particle size of the inorganic oxide powder in thefirst constraint layer and the second constraint layer will be describedbelow.

The case when the mean particle size of the inorganic oxide powder inthe first constraint layer 25 a is made to be equal to the mean particlesize of the inorganic oxide powder in the second constraint layer 25 b,or when the rigidity of the first constraint layer 25 a is made to beequal to the rigidity of the inorganic oxide powder in the secondconstraint layer 25 b, will be described first. An alumina powder wasused as the inorganic oxide powder herein, and the mean particle size(D50) of the alumina powder in each constraint layer was change within arange of 0.5 to 2.0 μm while changing the thickness of each constraintlayer within a range of 0.5 to 1.8 mm. The shrinkage ratio, dimensionalirregularity and the degree of warp of the ceramic multilayer substrate26 manufactured by the same method as shown in the second embodimentwere determined. The results of measurements are shown in TABLE 5. Thethickness of the multilayer ceramic body was adjusted to 1 mm in theseexamples.

TABLE 5 MEAN PARTICLE SIZE OF INORGANIC POWDER (μm) FIRST SECONDSHRINKAGE DIMENSIONAL DEGREE OF CONSTRAINT CONSTRAINT RATIO OF RATIODISTRIBUTION WARP EXAMPLE LAYER LAYER THICKNESS (%) (%) (μm/INCH²) 552.0 2.0 1.0 0.10 0.10 15 56 1.0 4.0 1.8 0.10 0.10 15 57 0.5 0.5 1.8 0.100.10 15 58 2.0 2.0 1.4 0.10 0.10 15 59 1.0 1.0 1.4 0.10 0.10 15 60 0.50.5 1.4 0.10 0.10 15 61 2.0 2.0 1.0 0.10 0.10 40 62 1.0 1.0 1.0 0.110.10 25 63 0.5 0.5 1.0 0.14 0.11 20 64 2.0 2.0 0.5 0.10 0.10 70 65 1.01.0 0.5 0.12 0.10 60 66 0.5 0.5 0.5 0.18 0.12 50 67 0.5 2.0 0.5 0.100.10 15 68 0.5 1.0 0.5 0.11 0.10 30 69 1.0 2.0 0.5 0.10 0.10 40

The examples 55 to 66 in TABLE 5 show that the shrinkage ratio,dimensional irregularity and the degree of warp can be well reduced at athickness of each constraint layer of 1.4 mm or more, irrespective ofthe mean particle size of the alumina powder. When the thickness of eachconstraint layer is as thin as 1.4 mm or less, on the contrary, thedegree of warp of the substrate tends to be increased. Although theshrinkage ratio as well as irregularity of the shrinkage ratio havetendencies to decrease when the mean particle size of the alumina powderis decreased, the degree of warp of the substrate showed a tendency toincrease. This is because the constraint layer itself causes a slightcontraction when the mean particle size of the alumina powder to be usedfor the constraint layer is reduced, but rigidity of the constraintlayer becomes high to hardly cause deformations such as warp.

The effect of the mean particle size of the alumina powder in eachconstraint layer having a thickness of 0.5 mm will be then described.The shrinkage ratio, dimensional irregularity and the degree of warp maybe well decreased when the mean particle size of the alumina powder inthe first constraint layer 25 a is made to be different from that in thesecond constraint layer 25 b besides adjusting the mean particle size ofthe alumina powder in the first constraint layer 25 a to be smaller thanthat in the second constraint layer 25 b as shown in the examples 76 to69 in TABLE 5. It was also made clear that the thickness of theconstraint layer required for sufficiently reducing the shrinkage ratio,dimensional irregularity and the degree of warp may be reduced to aboutone third as little as that described in the examples 55 to 60.

Fourth Embodiment

The optimum range of the organic binder in the first constraint layerand in the second constraint layer will be described below.

The case when the content of the organic binder in the first constraintlayer 25 a is adjusted to be equal to the content of the organic binderin the second constraint layer 25 b, or when the first constraint layer25 a is made to have the same rigidity as that of the second constraintlayer 25 b, fill be described first. A butyral based binder was used asthe organic binder in these examples, and the content of the organicbinder and the thickness of each constraint layer were changed within arange of 3 to 15 parts by weight relative to 100 parts by weight of theorganic binder in each constraint layer, and within a range of 0.5 to1.8 mm, respectively. The shrinkage ratio, dimensional irregularity andthe degree of warp of the ceramic multilayer substrate 26 manufacturedby the same method as in the second embodiment were determined, and theresults of measurements are shown in TABLE 6. The thickness of themultilayer ceramic body was adjusted to be 1 mm in these examples.

TABLE 6 CONTENT OF ORGANIC BINDER (PARTS BY WEIGHT) FIRST SECONDSHRINKAGE DIMENSIONAL DEGREE OF CONSTRAINT CONSTRAINT RATIO OF RATIODISTRIBUTION WARP EXAMPLE LAYER LAYER THICKNESS (%) (%) (μm/INCH²) 70 1515 1.8 0.10 0.10 15 71 12 12 1.8 0.10 0.10 15 72  9  9 1.8 0.10 0.10 1573  6  6 1.8 0.10 0.10 15 74  3  3 1.8 0.10 0.10 15 75 15 15 1.4 0.100.10 15 76 12 12 1.4 0.10 0.10 15 77  9  9 1.4 0.10 0.10 15 78  6  6 1.40.10 0.10 15 79  3  3 1.4 0.10 0.10 15 80 15 15 1.0 0.18 0.15 90 81 1212 1.0 0.10 0.10 60 82  9  9 1.0 0.10 0.10 40 83  6  6 1.0 0.10 0.10 3084  3  3 1.0 0.10 0.10 20 85 15 15 0.5 0.30 0.20 120  86 12 12 0.5 0.150.18 80 87  9  9 0.5 0.10 0.10 70 88  6  6 0.5 0.10 0.10 50 89  3  3 0.50.10 0.10 40 90  3  9 0.5 0.10 0.10 15 91  6 12 0.5 0.10 0.10 30 92  312 0.5 0.10 0.10 20

The examples 70 to 89 in TABLE 6 show that the shrinkage ratio,dimensional distribution and the degree of warp may be well decreased ata thickness of each constraint layer of 1.4 mm or more, irrespective ofthe content of the organic binder. However, the degree of warp of thesubstrate showed a tendency to increase when the thickness of eachconstraint layer is smaller than 1.4 mm. The shrinkage ratio,dimensional distribution and the degree of warp also showed a tendencyto increase when the content of the organic binder is increased. This isbecause the constraint layer itself caused a slight contraction when thecontent of the organic binder is increased, while decreasing therigidity of the constraint layer to readily cause warp of the constraintlayer.

The effect of the content of the organic binder when the thickness ofeach constraint layer is 0.5 mm will be described below. The examples 90to 92 in TABLE 6 show that the shrinkage ratio, dimensional irregularityand the degree of warp may be possibly decreased when the content of theorganic binder in the first constraint layer 25 a is further reduced.The results indicate that the thickness of the constraint layer requiredfor sufficiently reducing the shrinkage ratio, dimensional irregularityand the degree of warp can be decreased to about one third as small asthat in the examples 70 to 79.

Fifth Embodiment

The amount of addition of the fibrous inorganic oxide particles in thefirst constraint layer and in the second constraint layer will bedescribed below.

The case when the amount of addition of the fibrous inorganic oxideparticles into the first constraint layer 25 a was adjusted to be equalto that in the second constraint layer 25 b in FIGS. 6 and 7, or whenthe rigidity of each constraint layer was made to be equal, will bedescribed first. Fibrous alumina particles with a longitudinal axislength of 50 μm were used as the fibrous inorganic oxide particles,while the amount of addition of the fibrous inorganic oxide powder ineach constraint layer, and the thickness of each constraint layer werechanged within a range of 0 to 10% by weight and within a range of 0.5to 1.8 mm, respectively. The shrinkage ratio, dimensional irregularityand the degree of warp of the ceramic multilayer substrate 26 weredetermined by the same method as described in the second embodiment. Theresults of measurements are shown in TABLE 7. The thickness of themultilayer ceramic body was adjusted to be 1 mm in these examples.

TABLE 7 AMOUNT OF ADDITION OF FIBROUS INORGANIC PARTICLES (% BY WEIGHT)FIRST SECOND SHRINKAGE DIMENSIONAL DEGREE OF CONSTRAINT CONSTRAINT RATIOOF RATIO DISTRIBUTION WARP EXAMPLE LAYER LAYER THICKNESS (%) (%)(μm/INCH²)  93 20 20 1.8 0.10 0.10 15  94 15 15 1.8 0.10 0.10 15  95 1010 1.8 0.10 0.10 15  96  5  5 1.8 0.10 0.10 15  97  0  0 1.8 0.10 0.1015  98 20 20 1.4 0.10 0.10 15  99 15 15 1.4 0.10 0.10 15 100 10 10 1.40.10 0.10 15 101  5  5 1.4 0.10 0.10 15 102  0  0 1.4 0.10 0.10 15 10320 20 1.0 0.10 0.10 15 104 15 15 1.0 0.10 0.10 15 105 10 10 1.0 0.100.10 20 106  5  5 1.0 0.10 0.10 30 107  0  0 1.0 0.10 0.10 40 108 20 200.5 0.10 0.10 25 109 15 15 0.5 0.10 0.10 30 110 10 10 0.5 0.10 0.10 40111  5  5 0.5 0.10 0.10 50 112  0  0 0.5 0.10 0.10 70 113 20  0 0.5 0.100.10 15 114 20  5 0.5 0.10 0.10 15 115 15  0 0.5 0.10 0.10 15 116 15  50.5 0.10 0.10 15

The examples 93 to 112 in TABLE 7 show that the shrinkage ratio,dimensional irregularity and the degree of warp may be possiblydecreased at a thickness of each constraint layer of 1.4 mm or more,irrespective of the amount of addition of the fibrous inorganic oxideparticles. The shrinkage ratio, dimensional irregularity and the degreeof warp can be decreased to some extent by adding 5% by weight or moreof the fibrous inorganic oxide particles, even when the thickness ofeach constraint layer is adjusted to 1.0 mm. The degree of warp of thesubstrate showed a tendency to decrease as the amount of addition of thefibrous inorganic oxide particles is increased at the thickness of eachconstraint layer of 0.5 mm. This is because warp of the substrate hardlyoccurs when the amount of addition of the fibrous inorganic oxideparticles is increased.

The optimum amount of addition of the fibrous inorganic oxide particlesat a thickness of each constraint layer of 0.5 mm will be describedbelow. The examples 113 to 116 in TABLE 7 show that the shrinkage ratio,dimensional irregularity and the degree of warp can be well decreasedwhen the amount of addition of the fibrous inorganic oxide particlesinto the first constraint layer is increased, or when the fibrousinorganic oxide particles are added only in the first constraint layer.The thickness of the constraint layer required for sufficiently reducingthe shrinkage ratio, dimensional irregularity and the degree of warp canbe also decreased to about one half as small as that shown in theexamples 93 to 107 by the method as described above.

Sixth Embodiment

The amount of addition of the glass powder to be added in the first andsecond constraint layers will be described below.

The case when the same amount of the glass powder was added into eachconstraint layer, or when the rigidity of the first constraint layer 25a was made to be equal to the rigidity of the second constraint layer 25b, will be described first. A borosilicate glass powder was used as theglass powder in this embodiment, and the amount of addition of the glassin each constraint layer relative to all the component in the constraintlayer, and the thickness of each constraint layer were changed in arange of 0 to 0.7% by weight and in a range of 0.5 to 1.8 mm,respectively. The shrinkage ratio, dimensional irregularity and thedegree of warp of the ceramic multilayer substrate 26 obtained by thesame method as used in the second embodiment were measured, and theresults are shown in TABLE 8 below. The thickness of the multilayerceramic body 23 was adjusted to be 1 mm in this embodiment.

TABLE 8 AMOUNT OF ADDITION OF GLASS POWDER (% BY WEIGHT) FIRST SECONDSHRINKAGE DIMENSIONAL DEGREE OF CONSTRAINT CONSTRAINT RATIO OF RATIODISTRIBUTION WARP EXAMPLE LAYER LAYER THICKNESS (%) (%) (μm/INCH²) 1170   0   1.8 0.10 0.10 15 118 0.1 0.1 1.6 0.10 0.10 15 119 0.3 0.3 1.80.10 0.10 15 120 0.5 0.5 1.8 0.10 0.10 15 121 0.7 0.7 1.8 0.10 0.10 20122 0   0   1.4 0.10 0.10 15 123 0.1 0.1 1.4 0.10 0.10 15 124 0.3 0.31.4 0.10 0.10 15 125 0.5 0.5 1.4 0.10 0.10 15 126 0.7 0.7 1.4 0.12 0.1040 127 0   0   1.0 0.10 0.10 40 128 0.1 0.1 1.0 0.10 0.10 20 129 0.3 0.31.0 0.10 0.10 20 130 0.5 0.5 1.0 0.10 0.10 30 131 0.7 0.7 1.0 0.12 0.1040 132 0   0   0.5 0.10 0.10 70 133 0.1 0.1 0.5 0.10 0.10 30 134 0.3 0.30.5 0.10 0.10 25 135 0.5 0.5 0.5 0.10 0.10 50 136 0.7 0.7 0.5 0.13 0.11120  137 0.5 0   0.5 0.10 0.10 20 138 0.3 0   0.5 0.10 0.10 15 139 0.10   0.5 0.10 0.10 20

The examples 117 to 136 in TABLE 8 show that the shrinkage ratio,dimensional irregularity and the degree of warp may be well reduced at athickness of each constraint layer of 1.4 mm or more when the amount ofaddition of the glass powder is 0.5% or less. While the degree of warpof the substrate is reduced by adding the glass powder at a thickness ofeach constraint layer of 1.0 mm or less, the degree of warp and theshrinkage ratio showed increasing tendencies when the amount of additionof the glass powder is increased to 0.5% by weight or more. This isbecause, while the rigidity of the constraint layer increases by addingthe glass powder into the constraint layer, the constraint layer itselfis slightly contracted by adding a given amount or more of the glasspowder.

The amount of addition of the glass powder into each constraint layerwill be then described at a thickness of each constraint layer of 0.5mm. The examples 137 to 139 in TABLE 8 show that the shrinkage ratio,dimensional irregularity and the degree of warp may be suppressed byadding the glass powder only in the first constraint layer, 25 a. It wasalso possible by the process above to reduce the thickness of theconstraint layer required for sufficiently suppress the degree of warpto about one third as small as that in the examples 117 to 126.

Contraction of the non-sintered ceramic body along the X-Y directions,or contraction along the directions on the substrate plane, duringsintering may be sufficiently thy suppressed by forming the firstconstraint layer having a larger rigidity on one major surface sidehaving a larger shrinkage ratio by firing as described above. The degreeof warp of the substrate can be also sufficiently decreased whilerestricting the thickness of the constraint layer to its minimumessential thickness. Consequently, dimensional accuracy of the ceramicsubstrate can be improved besides suppressing the problem of wiringbreakage thanks to the small degree of warp of the substrate when a fineand highly integrated wiring pattern is formed.

While the present invention has been described based on the first tosixth embodiments, the present invention is not necessarily restrictedto the embodiments as set forth above, but various modifications thereofare possible.

For example, the equivalent circuits shown in FIGS. 5 and 8 are merelytypical examples for allowing the present invention to be easilycomprehended. Instead, the method for manufacturing the ceramicsubstrate according to the present invention may be equally-applied forother ceramic multilayer substrate containing a variety of circuitdesigns. Various surface-mounting members such as laminated ceramiccapacitors and semiconductor devices may be also mounted on the ceramicsubstrate obtained. The molded block to be integrated into thenon-sintered ceramic body is not restricted to elementary members suchas capacitors and inductors, but it may be a molded block of a LCcomposite member.

The method for manufacturing the ceramic substrate according to thepresent invention can be applied for various module substrates such asIC package substrates and hybrid IC substrates, as well as formanufacturing laminated chip members such as multilayer filters,multilayer chip antennas and multilayer ceramic capacitors.

The method for manufacturing the ceramic substrate according to thepresent invention is favorably applied for the non-sintered ceramic bodyas a precursor of the ceramic substrate comprising laminated greensheets (a multilayer ceramic body) prepared by laminating the greensheets comprising conductor patterns, wherein (1) the degree ofintegration of the conductor pattern is different at the upper side andlower side with respect to the center face located at the same distancefrom both major surfaces of the laminated ceramic green sheets, (2)plural kinds of the ceramic green sheets having mutually differentcompositions are laminated, and (3) plural kinds of the ceramic greensheets having mutually different thicknesses are laminated. Otherwise,the non-sintered ceramic body constructed as described above is liableto cause warp and distortion ascribed to the difference of the degree ofcontraction by firing at the upper and lower sides of the non-sinteredceramic body.

More practically, the constraint layer having a higher rigidity may beapplied on the side having a higher degree, of integration of thesemiconductor pattern, because the laminated body tends to form concavewarp toward the side having a higher degree of integration of thesemiconductor pattern when the ceramic laminated body has differentdegree of integration on the upper side and lower side with respect tothe center face located at the same distance from both major surfaces ofthe green sheet laminated body. When the green sheet laminated bodycomprises laminated plural kinds of ceramic green sheets having mutuallydifferent compositions (ceramic green sheets having differentcompositions and particle sizes of the ceramic), a constraint layerhaving a higher rigidity may be applied on the side capable of beingmore largely contracted during firing with respect to the center facelocated at an equal distance from the both major surfaces of the greensheet laminated body. When the ceramic laminated body compriseslaminated plural kinds of the ceramic green sheets having mutuallydifferent thicknesses, the constraint layer having a higher rigidity maybe applied on the side representing a thicker green sheet because theceramic green sheet may be more largely contracted when it is thicker.

While the rigidity of each constraint layer may be appropriatelyselected by repeated try-and-error, it is desirable to select suchrigidity as is able to minimize the degree of warp of the substrate bypredicting, for example, the relations between the degree of integrationof the conductor pattern and the degree of warp, between the compositionof the ceramic green sheet and the degree of warp of the substrate, andbetween the thickness of the ceramic green sheet and the degree of warpof the substrate, as well as the relation between the degree of warp ofthe substrate and rigidity of the constraint layer.

The present invention relates to a non-fired ceramic substrate preparedby adhering a first constraint layer and second constraint layer on onemajor surface and the other major surface, respectively, of anon-sintered ceramic body comprising a conductor pattern, the first andsecond constraint layers mainly comprising an inorganic powder that isnot sintered at the sintering condition of the non-sintered ceramic bodyand having different rigidity one another. Rigidity of the firstconstraint layer and the second constraint layer is appropriatelyselected based on the first to fifth methods as hitherto described.

In the method for manufacturing the ceramic substrate according to thepresent invention, the first constraint layer and the second constraintlayer is adhered on one major surface and the other major surface,respectively, of the non-sintered ceramic body comprising a conductorpattern, the first and second constraint layers mainly comprising aninorganic powder that is not sintered under the sintering condition ofthe non-sintered ceramic body, and each constraint layer is removedafter firing under the sintering condition of the non-sintered ceramicbody. The rigidity of the first constraint layer and the rigidity of thesecond constraint layer may be different one another and may beappropriately selected so as to suppress deformation of the ceramicsubstrate by firing. Consequently, a ceramic substrate having anexcellent dimensional accuracy can be efficiently manufactured bysuppressing firing contraction along the directions on the substrateplane, besides suppressing substrate deformation such as warp of thesubstrate.

Making the first constraint layer to have higher rigidity than thesecond constraint layer, and allowing the first constraint layer toadhere on one major surface that may be more largely contract by firing,make it possible to sufficiently suppress warp and distortion of thesubstrate ascribed to differences of contraction between one majorsurface and the other major surface of the non-sintered ceramic body,thereby allowing a ceramic substrate having an excellent dimensionalaccuracy to be readily and efficiently manufactured by sufficientlysuppressing deformation of the substrate without using any specialfiring equipment.

Since the constraint layer should not have film thickness more thannecessary, the manufacturing cost required for the constraint layer isdepressed and peeling and removal of the constraint layer after firingturn out to be quite easy. Moreover, since the organic binder in theconstraint layer and in the non-sintered ceramic body is smoothlyvolatilized, the firing time is shortened to reduce irregular firing andto suppress generation of pores due to residues of the organic binder,thereby enabling a high quality ceramic substrate to be manufactured.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that the forgoing and other changes in form anddetails may be made therein without departing from the spirit of theinvention.

What is claimed is:
 1. A method for manufacturing a ceramic substratehaving conductor patterns, comprising: adhering a first constraint layeron a first major surface of a non-sintered ceramic body, the firstconstraint layer being mainly composed of a first inorganic powder thatis not sintered under the sintering condition of the non-sinteredceramic body; adhering a second constraint layer on a second majorsurface of the non-sintered ceramic body, the second constraint layerbeing mainly composed of a second inorganic powder that is not sinteredunder the sintering condition of the non-sintered ceramic body; andremoving each of the first and second constraint layers after firing thenon-sintered ceramic body under the sintering condition of thenon-sintered ceramic body; wherein the first constraint layer and thesecond constraint layer are made to have different rigidity from oneanother.
 2. The method for manufacturing a ceramic substrate accordingto claim 1, wherein the first constraint layer is made to have a higherrigidity than that of the second constraint layer, said first constraintlayer being adhered on one major surface side that is able to be largelycontracted by firing.
 3. The method for manufacturing a ceramicsubstrate according to claim 1, wherein the first constraint layer isformed to have a thickness larger than the thickness of the secondconstraint layer.
 4. The method for manufacturing a ceramic substrateaccording to claim 3, wherein the first constraint layer is formed tohave a thickness three times or less as large as the thickness of thesecond constraint layer.
 5. The method for manufacturing a ceramicsubstrate according to claim 1, wherein the mean particle size of theinorganic oxide powder in the first constraint layer is made to besmaller than the mean particle size of the inorganic oxide powder in thesecond constraint layer.
 6. The method for manufacturing a ceramicsubstrate according to claim 1, wherein the first constraint layer andthe second constraint layer are formed by dispersing the inorganicpowder in an organic binder, the content of the organic binder in thefirst constraint layer being made to be smaller than the content of theorganic binder in the second constraint layer.
 7. The method formanufacturing a ceramic substrate according to claim 1, wherein thefirst constraint layer contains fibrous inorganic oxide particles. 8.The method for manufacturing a ceramic substrate according to claim 1,wherein the first constraint layer contains a glass powder that does notexhibit viscous fluidity under the sintering condition of thenon-sintered ceramic body in the first constraint layer.
 9. The methodfor manufacturing a ceramic substrate according to claim 1, wherein thefirst constraint layer and the second constraint layer serve as ceramicgreen sheets comprising an inorganic oxide powder dispersed into anorganic binder.
 10. The method for manufacturing a ceramic substrateaccording to claim 1, wherein the non-sintered ceramic body compriseslaminated green sheets prepared by laminating ceramic green sheetshaving the conductive patterns, the degree of integration of theconductor patterns being different between the upper side and lower sidewith respect to the center face located at an equal distance from theboth major surfaces of the laminated member of the ceramic green sheets.11. The method for manufacturing a ceramic substrate according to claim1, wherein the non-sintered ceramic body comprises laminated greensheets prepared by laminating ceramic green sheets having the conductorpatterns, plural kinds of the ceramic green sheets having mutuallydifferent compositions being laminated in the non-sintered ceramic body.12. The method for manufacturing a ceramic substrate according to claim1, wherein the non-sintered ceramic body comprises laminated greensheets prepared by laminating ceramic green sheets having the conductorpatterns, plural kinds of the ceramic green sheets having mutuallydifferent thicknesses being laminated in the non-sintered ceramic body.13. The method for manufacturing a ceramic substrate according to claim1, wherein at least one kind of passive member selected from the groupconsisting of a capacitor, an inductor and a resistor is integrated intothe non-sintered ceramic body.
 14. The method for manufacturing aceramic substrate according claim 13, wherein the capacitor or theinductor is integrated into the non-sintered ceramic substrate as ablock member.
 15. The method for manufacturing a ceramic substrateaccording to claim 1, wherein the non-sintered ceramic body is fired ata firing temperature of 1000° C. or below.
 16. The method formanufacturing a ceramic substrate according to claim 1, wherein thenon-sintered ceramic body is fired without applying any load.
 17. Thenon-fired ceramic substrate prepared by adhering a first constraintlayer and a second constraint layer on both major surfaces of anon-sintered ceramic body, respectively; the non-sintered ceramic bodycomprising conductor patterns; and the first constraint layer and thesecond constraint layer containing inorganic powder that is not sinteredunder the sintering condition of the non-sintered ceramic body as aprincipal component, and having different rigidities from one another.